An image forming apparatus is known which forms an image with a color toner. By irradiating the surface of a photoconductive drum with scanning beams, the image forming apparatus forms an electrostatic latent image on the photoconductive drum. The image forming apparatus develops the electrostatic latent image into a toner image.
For example, the image forming apparatus is equipped with a plurality of photoconductive drums. The image forming apparatus separately irradiates each photoconductive drum with scanning beams. The toner images on the photoconductive drums are required to be accurately aligned in relative position between the photoconductive drums. Particularly, the quality of the image is degraded when the scan positions of the scanning beams are not parallel.
Thus, in the image forming apparatus, the positions of a plurality of mirrors for reflecting scanning beams are adjusted. The adjustment is carried out while the positions of the scanning beams are measured. A position adjustment unit for changing the position of a mirror is arranged inside the image forming apparatus.
However, more than four scanning beams are needed to form a full-color image. More than three position adjustment units each of which is equipped with a motor are needed to adjust the positions of mirrors. The configuration of the motors and motor control circuits increases the cost of the image forming apparatus.